MAGNETIC EFFECT OF CURRENT
Magnet is oxide of iron which has the property of attracting small pieces of iron, steel, cobalt and nickel towards itself. Magnet was discovered about 2500 years ago by Greeks in the form of a black ore of iron called loadstone. Now days, loadstone is called magnetite which have chemical formula (Fe3O4). Magnets are very useful to us. They are used in loudspeakers, microphones, electric motors, door bells, VCRs, CD players, music systems and many other things.
A magnet always consists of two poles: north pole and south pole. When a magnet is suspended in the air, it always points in north and south direction of earth. The end of magnet which points towards the north direction of earth when suspended freely is called north pole of the magnet. On the other hand, the end of magnet which points towards the south direction of earth when suspended freely is called south pole of the magnet.
The sure test of magnetism is repulsion, i.e. when a piece of iron is brought near the two poles of the magnet then it is attracted by both the poles of the magnet. But when a magnet is brought near the second magnet then it is attracted by one pole of second magnet and repelled by other pole of second magnet.
Properties of a Magnet
Following are the important properties of a magnet:
- A magnet always attracts magnetic substances like iron, steel, cobalt and nickel towards itself.
- When a magnet is suspended freely in the air, it always points in north and south direction of earth.
- Like poles of a magnet repel each other whereas unlike poles of magnet attract each other.
- Magnetic poles always exist in pairs, i.e. when a magnet is broken into two or more pieces; each small part of the magnet is a complete magnet in itself.
Test Your Understanding and Answer These Questions:
- Define magnet. Give its two important properties.
- Repulsion is the sure test of magnetism. Explain.
- Magnetic poles always exist in pairs. Comment.
- Name three magnetic materials.
- Give uses of a magnet.
- Define north pole of a magnet.
- Define south pole of a magnet.
- In which directions does a magnet point when suspended freely?
- Can the poles of a magnet be separated?
- Name the ore of iron which is used as magnet.
- What is the chemical formula of loadstone?